No-Load Loss Separation of High-Speed Electric Motors for Electrically-Assisted Turbochargers

This article presents a testing procedure for the no-load loss separation of high-speed electric machines designed for Electrically-Assisted Turbochargers. The main contribution of this paper is to introduce a loss separation method suitable for low power (several kW) high-speed electric motors. The paper begins by presenting the environmental context of the study, the overall system and motivations to develop such a method. Then, the experimental procedure using several back-to-back (B2B) configurations supported by an air bearing is proposed to identify the no-load losses including: no-load iron, air bearing and windage losses. Finally, the method is applied to three stator topologies to compare the no-load iron losses levels. The presented principle enables a no-load loss separation for very high-speed machines in the range of several kilowatts without the use of a torque meter. In addition, the identification of the air bearing losses makes possible the evaluation of the motor efficiency on the presented B2B test bench without any major modifications.